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reddal 25th January 2012 06:47 AM

Fostex Drivers
I just got my hands on some old Fostex Drivers, but I can't find any spec or information on them.

I was hoping that someone here could help out.

The first Pair is "Fostex 100 F04"
And the second pair is "Fostex Fe103 Zigma"

I would like recomended enclosures, and specs.


planet10 25th January 2012 07:31 AM

Pictures would be useful.

FE103 Sigma (no Z) us going to be a special edition FE103. The other is likely an older FE103 variant,


reddal 25th January 2012 09:34 AM


Thanks for replying.

The FE103 is Zigma's, With the greek symbol.

Will take some pictures later.


reddal 25th January 2012 09:49 AM

4 Attachment(s)
Fostex 104F04

Fostex FE103 Zigma


Scottmoose 25th January 2012 11:59 AM

Σ = upper case 'Sigma.'

There is a certain amount of information out there.

FE103Σ - Google Search

The FE103Sigma was a variation on the old FE103, with a larger magnet structure. Fostex in this period didn't put out a particularly comprehensive set of data (they still don't for most Japan-only special editions). This is about as much as you're likely to find from them:

The French magazine Audiophile from 1984 gives some information: Le Fostex FE-103 Sigma

And the German magazine Klang+Ton measured some specs. back in 2000, when it was near the end of its life: -note that at the time Fostex units were often sold under the ACR brand name.

And here's another box: La Petite Audiophile

I can't comment on the designs; I only spent about 5 minutes looking & don't have time at present to back-engineer them. Since they're older units, it's likely that they've drifted from the factory spec. anyway.

reddal 25th January 2012 05:13 PM

Thanks, I have, like you, found some info on he sigma, but i didnt know that it also was sold under ACR name. Good info.

I still havent found much on the other driver, so if someone has some info, i appriciate it.


phivates 25th January 2012 10:44 PM

That looks a lot like my pair out of a Singer (KLH) portable from the sixties. Numbers: DS-423
7 8 - 4 5
8 ohm 3 W

Pictures will follow I swear

planet10 26th January 2012 12:28 AM


Originally Posted by reddal (
The FE103 is Zigma's, With the greek symbol.

The greek symbol is Sigma. Zigma is bad Japanese for the symbol.


Edit: I see Scott beat me to that... bears repeating

planet10 26th January 2012 12:32 AM

The 1st is an FE103 varient. Bigger magnet than the last 3 generations. Made in Japan probably dates it to the late 70s, or the 80s.

The 103Σ is based on the same platform, probably differing only by having an even larger magnet. Yours has had some leakage from the surround glue onto the cone, you should check to see how well attached it is (very common in the even older alnico version of these drivers)


planet10 26th January 2012 12:35 AM


Originally Posted by reddal (
but i didnt know that it also was sold under ACR name.

The ACRs were a 1 off batch made with an extra magnet.


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